Serum cystatin C and emphysema: results from the National Health and Nutrition Examination Survey (NHANES).

Abstract

BACKGROUND:

Cystatin C (CysC) is a potent nonorgan-specific cysteine protease inhibitor and may contribute to elastolysis and tissue destruction by a mechanism of protease–antiprotease imbalance. Given the prevalence of CysC in the serum of smokers and its role in tissue destruction, we aimed to evaluate the association between CysC and emphysema.

METHODS:

Pooled cross-sectional data from the National Health and Nutrition Examination Survey 1999–2002 were used. Emphysema and chronic bronchitis were defined by a self-reported history ascertained using standardized questionnaires. Active smokers were defined as self-reported current smokers or measured serum cotinine ≥10 ng/mL. Nonactive smokers with a serum cotinine level >0.05 ng/mL were defined as environmental tobacco smoke (ETS)-exposed.

CONCLUSION:

In a large representative noninstitutionalized US population, we demonstrated an association between emphysema and serum CysC. Active smokers with emphysema had significantly higher CysC levels. These findings suggest that CysC may play a role in the pathogenesis of smoking-related emphysema.